Filtering devices are used in a wide variety of environments including, for example, industrial buildings and surface maintenance equipment. A wide variety of machines is available for use in maintenance of surfaces such as floors, parking lots and streets. These maintenance machines generally include sweeping machines and scrubbing machines. The sweeping machines utilize fans or pumps to draw a vacuum in the brush housing thereby minimizing dusting problems around the sweeping area. A problem which has been long existent in the prior art, is the accumulation of dust on the filter. As the dust accumulates, it tends to block the filter and create a substantial pressure differential between the upstream side of the filter and the downstream side of the filter. Such blockage reduces the dust controlling efficiency of the equipment. Many attempts have been made in the past to overcome such blockage problem generally by vibration or shaking of the filter. Such arrangements have improved the efficiency by removing the dust accumulations to a certain extent. The shaking of the filter, however, has not been as effective in removing the dust as would be desirable.